Version July 2025
| M. streptocera | M. ozzardi | M. perstans | |
| Geographic distribution | Western and Central Africa | Central and South America, Caribbean | Sub-Saharan and North Africa, South America |
| Transmission | Transmitted via bite of infected Culicoides species (midge) | Transmitted via bite of infected Culicoides species (midge) or by Simulium amazonicum (black fly) | Transmitted via bite of infected Culicoides species (various species) |
| Clinical features | Usually asymptomatic but can cause chronic papulonodular dermatitis, pruritis, pigmentation changes, dermal thickening, and lymphadenopathy. May be difficult to distinguish from onchocerciasis. | Usually asymptomatic but can be associated with urticaria, pruritic rash, edema, lymphadenopathy, arthralgias, fever, headache, vertigo, or pulmonary symptoms. | Usually asymptomatic but can cause transient angioedema, urticaria, and pruritus and may be difficult to distinguish from loiasis. Other manifestations include headache, arthralgias, pericarditis, pleuritis, hepatitis, meningoencephalitis, and ocular symptoms. |
| Site of adult parasites | Dermal layers of the trunk and upper shoulder girdle | Lymphatics and thoracic and peritoneal cavities | Pericardial, pleural and peritoneal cavities; mesenteric, perirenal, and retroperitoneal tissues |
| Site of microfilariae | Skin | Blood and skin | Blood |
| Diagnosis | Microfilariae in skin snips. Differentiated from mf of Onchocerca volvulus by small size (180 to 240 micrometers) and characteristic sharp curve in tip of tail ("shepherd's crook"). | Microfilariae in blood and occasionally in skin snips. Differentiated from other circulating mf by lack of significant periodicity, small size (170 to 240 micrometers long), absence of sheath, and absence of terminal nuclei. | Microfilariae in blood (or rarely serosal effusions). Differentiated from other circulating mf by lack of significant periodicity, small size (190 to 200 micrometers), absence of sheath, and round terminal nucleus at the tip of the tail. |
| Other laboratory findings | Peripheral eosinophilia is common | Peripheral eosinophilia is common | Peripheral eosinophilia and elevated serum IgE are common |
| Treatment | Diethylcarbamazine (6 mg/kg/day orally for 14 days) is effective against adults and microfilariae but associated with significant side effects. Ivermectin (150 mcg/kg orally) is effective in reducing microfilariae.[1] | Ivermectin (200 mcg/kg orally) is the treatment of choice.[2-3] Diethylcarbamazine is ineffective.[4] | Recommend therapy with albendazole (400 mg orally twice daily for 10 days) or mebendazole (100 mg orally twice daily for 30 days) is generally ineffective.[5] Doxycycline (200 mg orally daily for six weeks) clears microfilariae for up to 36 months.[6] |
